Accelerating pump vent



March 24, 1959 M. L. SMITLEY ACCELERATING PUMP VENT Filed Sept. 24, 1956MAP/0N B IN VEN TOR. L. 5/14/71.

b WM A.

United States Pate at ACCELERATIN G PUMP VENT Marion L. S mitley,Huntington Woods, Mich., assignor to Holley Carburetor Company, VanDyke, Mich., a mma on of M chiga Application September 24, .1956, SerialNo.'611,417

7 Claims. (Cl. 261-34) This invention relates to accelerating pumps forcarburetors and the like, and more particularly to an accelerating pumphaving an automatically operated vent which greatly improves theoperation of the pump.

Most carburetors or other fuel controls are provided with anaccelerating pump adapted to discharge additional fuel to the enginewhen the supply of airto the engine is suddenly increased. Suchaccelerating pumps usually comprise a chamber having a movable wall, apiston or a diaphragm for example, connected in some manner to thethrottle linkage. When the throttle is opened, the diaphragm is movedinto the chamber so that fuel is discharged to the engine; when thediaphragm is moved away from the chamber, the chamber is filled withfuel from the float chamber. The necessary check valves are provided toinsure a one-way flow of fuel in either case.

It has been found that when the engine is shut down after a suflicientperiod of operation so that the engine is hot, the fuel in theaccelerating pump chamber vaporizes. This often forces some additionalfuel to be discharged into the engine intake passage, and this loadingof the engine with fuel causes hard restarting. Also, a pocket of vaporis often trapped in the upper portion of the chamber. In either case,when the engine is restarted, -actuation of the accelerating pumpresults in an inade quate amount of fuel being supplied to the engine.'If a vapor pocket is present, this dangerous deficiency of fuelcontinues to occur until the vapor pocket is in some way removed; Theseobjections to present fuel accelerating pumps cannot be corrected by asimple open vent, since it would make the accelerating pump useless.

It is now proposed to provide an accelerating pump structure havingautomatic means to vent the accelerating pump chamber when the engine isnot operating so that any vapors that form may escape before the engineis restarted. With the proposed structure, the vent will be closedwhenever the engine is operating and the accelerating pump is operated.

This and other objects of the invention will become more readilyapparent by reference to the following specification and the attacheddrawing, wherein:

The figure is a side elevational view, with portions thereof cut awayand in cross section, of a carburetor having an accelerating pumpembodying the invention.

Referring to the drawings in greater detail, a carburetor 10 is formedto provide the usual air intake portion 12 and the throttle body portion14. The air intake portion :12 may be provided with a flange 16 andshoulder 18 adapted to support the flange 20 of an ordinary air cleaner22 The air intake portion 12 may be further formed externally to providean open recess 24 which, together with the gasket 26 and the cover 28secured by bolts 30, forms a closed float chamber 32. In accordance withwell known practice, the float chamber 32 is continuously vented to theair intake portion 12 or the air cleaner 22 by means of the open tube34.

2 The inner wall 36 of the recess 24 and the blockmember 38 areconstructed so that when the block member 38 is secured to the innerwall 36, with a flexible diaphragm 40 interposed therebetween, opposingchambers 42 and 44 having a common wall are formed. The chamber 44 isconnected to the float chamber by means of a passage 46 having agravity-actuated ball check valve 48 therein normally engaging the seat50. In addition, the chamber 44 is connected to the air intake passage52 by means of a passage 54 having a spring-loaded check valve 56therein normally engaging the seat 58. A compression spring 60 isdisposed between the block member 38 and the usual washer member 62supporting the center of ,the flexible diaphragm 40. Extending from thewasher member 64 supporting vthe other side of the diaphragm 40 is a rod66 extending through the passage 68 communicating with the chamber 42and into the .hollow cylindrical member 70.

The throttle body portion 14 of the carburetor .10 is provided with athrottle shaft 72 having a throttle lever 74 connected for rotationtherewith. The link 76, is pivoted at one end to the throttle lever 74and at the other end to the accelerating pump lever 76 having theportion 78 thereof adapted to engage the hollow cylindrical member 70.As is Well known in the art, when the throttle is opened theaccelerating pump lever 76 is rotated clockwise, by reason of itsconnection to the throttle lever 74, in a manner to urge the hollowcylindrical member 70 to the right to compress the spring 80 extendingalong the rod 66 between the free end v82 of the .hollow cylindricalmember 70 and the washer 64.

The spring 80 urges the diaphragm 40 into the chamber 44 against thecompression .spring 69, which opens the spring-loaded check valve 56 andpermits fuel to be discharged through the passage 54, the jet 184 andthe orifice 86 and into the intake passage 52. When the throttle isclosed, the compression spring 60 is free to urge the diaphragm 40 tothe left, thus opening the check yalve 58 and refilling the chamber 44.

The structure described above for purposes of illustration is typical inprinciple of most accelerating pumps presently employed.

When the engine 88 is shut down while hot, the car buretor 1 0 alsoimmediately becomes hot due to the ab,- sence of the cooling effect ofthe fan and the flow of air throughand around the carburetor 10. This isparticularly true with the newer carburetors that are built low to theengine so as to permit lowering of the automobile hood. When thisoccurs, the fuel in the chamber 44 begins to vaporize or boil, just asit does in the fioat chamber 32, resulting in the objections alreadymentioned above. It is apparent that any vapors formed in the floatchamber 32, whether or not the engine is running, are continuously drawnoff or permitted to rise through the open tube 34. However, the vchamber44 of the acceler ating pump cannot be continuously vented because theaccelerating pump 91) must be maintained in a filled condition and readyto be operated, at least while the in is unnin In accordance with theinvention, which eliminates the above objections, a passage 92 is formedin the block member 38 in a manner to provide communication between theupper portion of the chamber 44 and the tube he P sa 92. s fo m d t inud a $3 4 a p d to b eng ge by h ba l he k al e the bal .6, which isrelatively small as compared to the inlet ball 48, is preferably made ofa light weight non-absorbent material such as nylon and is preventedfrom dropping into the chamber 44 by means of a pin 98 extending fromthe wall of the passage 92. The pin 98 is preferably located so that theball 96 is maintained in close proximity within the air cleaner 22 orthe intake passage 52 instant-- 1y drops to below atmospheric due to therestriction provided by the air cleaner. This pressure drop, which maybe equal to /2 inch of water, is suflicient to immediatelylift the ball96 against the seat 94. The lifting action on the ball 96 is due tothefact that previous to starting, the ball 96 is in an unseated positionand therefore the chamber below it is at atmospheric pressure. Themoment the engine starts, however, the ball, being in close proximity toits seat and having a very small mass, is quickly seated by thedifierential pressure which is applied to it.

Of course, as the speed of the engine increases the pressure drop acrossthe air cleaner is greater and may become equal to more than a pressuredifferential of 3.00 inches of Water. This means that during the higherspeed ranges where the accelerating pump is required to deliveradditional fuel, the force holding the ball 96 seated is six times asgreat as that which initially was required to move it to its seatedposition. This added force, plus the fact that the diameter of vent 95is much smaller than the diameter of inlet 47, prevents the ball 96 fromfalling during the pump inlet stroke. However, as soon as the engine isshut down, the ball 96 drops down to the pin 94 as shown in the figureso that any vapors formed in the chamber 44 may pass upwardly around theball 96 and into the intake passage 52 through the tube 34. As soon asthe engine is restarted, the ball 96 is again seated to close thepassage 92.

While but a single form of the invention has been disclosed for purposesof illustration, it is apparent that various other forms may be adoptedwithout exceeding the scope of the invention, and no limitations areintended except those recited in the following claims:

What I claim is:

1. A fuel control for an internal combustion engine, comprising a bodyformed to provide an air intake passage, a throttle controlling the flowof air through said passage, a fuel bowl adjacent said air intakepassage, said fuel bowl being vented to said air intake passage, anaccelerating pump including a chamber disposed below said fuel bowl ventand filled by fuel from said fuel bowl, said chamber having a ventconnecting all vapor trapping portions of said chamber with said fuelbowl vent, said chamber vent having a valve responsive to operation ofsaid engine in a manner to close said vent whenever said engine isrunning, said valve being opened only when said engine is not running.

2. A fuel control for an internal combustion engine, comprising a bodyformed to provide an air intake passage, a throttle controlling the flowof air through said passage, a fuel bowl adjacent said air intakepassage, said fuel bowl being continuously vented to said air intakepassage, an accelerating pump including a, chamber disposed below saidfuel bowl vent and filled by fuel from said fuel bowl, said chamberhaving a fuel inlet, a fuel outlet and a separate vent passageconnecting said fuel bowl vent with all vapor trapping portions in theuppermost portion of said chamber, said chamber vent being provided witha valve responsive to operation of said engine in a manner to close saidvent whenever said engine is running, and to open said valve only whensaid engine is not running.

3. A fuel control having an air intake passage, an accelerating pumpadapted to supply additional amounts of fuel to said intake passage,spid accelerating pump including a fuel chamber, and automatic means forventing said chamber to said intake passage at all times except when airflows through said intake passage, said venting means including a valveresponsive to air flow through said intake passage.

4. A fuel control for an internal combustion engine, comprising an airintake passage, an accelerating pump adapted to supply additionalamounts of fuel to said intake passage, said accelerating pump includinga fuel chamber, and automatic means including a valve responsive tooperation of said engine for ventingall vapor adapted to supplyadditional amounts of fuel to said intake passage, said acceleratingpump including a fuel chamber, and automatic means for venting theentire volume of said chamber only when said engine is not operating,said automatic means including a valve responsive to operation of saidengine for preventing venting when said engine is operating.

6. A fuel control for an internal combustion engine, comprising an airintake passage, said intake passage having a throttle valve therein, andan accelerating pump 'connected with said throttle valve in a manner tosupply additional fuel to said intake passage when said throttle valveis opened, said accelerating pump including a chamber having a movablewall the movement of which into said chamber by means of its connectionto said throttle valve causes fuel to be discharged from said chamberand into said air intake passage, the entire volume of said chamberbeing vented by a passage extending upwardly from the upper portion ofsaid chamber to said air intake passage, said passage having a valveresponsive to engine operation and adapted to be closed when said engineis operating and opened when said engine is not operating.

7. A fuel control for an internal combustion engine having an aircleaner, comprising an air intake passage subject to air cleanerdepression when said engine is operating, said intake passage having athrottle valve therein, and an accelerating pump connected with saidthrottle valve in a manner to supply additional fuel to said intakepassage when said throttle valve is opened, said accelerating pumpincluding a chamber having a fuel inlet passage, a fuel outlet passageand a movable wall the movement of which into said chamber by means ofits con- References Cited in the file of this patent UNITED STATESPATENTS 2,109,260 Chandler et al. Feb. 22, 1938 2,182,393 Ball et al.Dec. 5, 1939 2,406,114 Sloane et al. Aug. 20, 1946 2,619,333 Carrey Nov.25, 1952 2,658,733 Boller Nov. 10, 1953; 2,775,436 Zub Dec. 25, 1956

